The advertising standards watchdog has closed its investigation into a website linked to Conservative Party chairman Grant Shapps after receiving assurances on its use of pseudonyms and testimonials.

The Advertising Standards Authority launched a probe into How To Corp after receiving complaints that the website misleadingly implied that the pen name Michael Green, formerly used by Mr Shapps, was a real person, and that testimonials were not genuine.

Mr Shapps founded the website, which offered money-making advice, before going into Parliament, but transferred his share in the business to his wife Belinda in 2008 and says he has had nothing to do with it in recent years.

But he has been dogged by allegations relating to the website during this week's Conservative conference in Birmingham. Channel 4 News broadcast footage of him being pursued through a series of doors backstage at the conference by reporter Michael Crick, as he tried to put questions to him.

An ASA spokesman said today: "We have resolved the matter informally with How To Corp. We have received assurances that the marketer will in future make clear if pseudonyms are used and that they will not use testimonials in the absence of adequate evidence."